Brillouin溫度測量儀信號探測與處理技術研究
發(fā)布時間：2019-03-17 18:14
【摘要】：分布式光纖布里淵傳感技術是近年來發(fā)展起來的一項新的傳感技術,它具有測量精度高、傳感距離遠等優(yōu)點,并且可以同時對溫度和應變進行分布測量,因此非常適用于處于惡劣環(huán)境中的大型工程結構的健康監(jiān)測,具有非常重要的應用前景本文基于BOTDA技術原理,對Bri1llouin溫度測量儀的信號探測與處理技術進行了較為深入和系統(tǒng)的研究。提出了利用聲光和電光相結合進行移頻的方法,解決了現有基于電光移頻的BOTDA技術原理中存在兩邊帶對泵浦光能量的相互抵消問題。設計了以工控機為核心的信號探測、處理與控制電路軟硬件,電路設計包括以FPGA和高速放大器構成的可調窄脈沖電路和光電探測電路,其中可調窄脈沖電路可以由計算機控制輸出任意脈沖寬度的窄脈沖,最小脈寬可達5ns；光電探測電路由I/V轉換電路、信號放大濾波電路和電壓轉換電路等組成,可以對脈寬為10ns,強度小于-50dBm的光脈沖信號進行探測。信號處理采用了對采樣數據的預處理、BOCAX積分、小波變換等方法,提高了測量數據的信噪比。采用非線性最小二乘法對測量數據進行洛倫茲擬合,最后通過布里淵譜計算出分布溫度數據。搭建了分布式光纖布里淵溫度測量系統(tǒng)實驗裝置,通過實驗溫度分辨率達到10C,空間分辨率達到1m。
[Abstract]:Distributed optical fiber Brillouin sensing technology is a new sensing technology developed in recent years. It has the advantages of high measurement precision, long sensing distance, and can simultaneously measure temperature and strain distribution. Therefore, it is very suitable for the health monitoring of large-scale engineering structures in harsh environment, and has a very important application prospect. This paper is based on the principle of BOTDA technology. The signal detection and processing technology of Bri1llouin temperature measuring instrument is studied deeply and systematically. The method of combining acousto-optic and electro-optic to shift frequency is put forward, which solves the problem of mutually counteracting the energy of pump light in the principle of BOTDA based on electro-optic frequency shift. The hardware and software of signal detection, processing and control circuit based on industrial control computer are designed. The circuit design includes adjustable narrow pulse circuit and photoelectric detection circuit composed of FPGA and high speed amplifier. The adjustable narrow pulse circuit can be controlled by computer to output narrow pulse with arbitrary pulse width, and the minimum pulse width can reach 5 ns. The photoelectric detection circuit is composed of I / V conversion circuit, signal amplifying filter circuit and voltage conversion circuit. It can detect the optical pulse signal whose pulse width is 10 ns and the intensity is less than-50dBm. In signal processing, the signal-to-noise ratio (SNR) of the measured data is improved by pretreatment of sampled data, BOCAX integral, wavelet transform and so on. The nonlinear least square method is used to fit the measured data in Lorentz. Finally, the distribution temperature data are calculated by Brillouin spectrum. The experimental equipment of distributed optical fiber Brillouin temperature measurement system is built. The experimental temperature resolution reaches 10C and the spatial resolution reaches 1m.
【學位授予單位】：北京化工大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TH811
本文編號：2442564
[Abstract]:Distributed optical fiber Brillouin sensing technology is a new sensing technology developed in recent years. It has the advantages of high measurement precision, long sensing distance, and can simultaneously measure temperature and strain distribution. Therefore, it is very suitable for the health monitoring of large-scale engineering structures in harsh environment, and has a very important application prospect. This paper is based on the principle of BOTDA technology. The signal detection and processing technology of Bri1llouin temperature measuring instrument is studied deeply and systematically. The method of combining acousto-optic and electro-optic to shift frequency is put forward, which solves the problem of mutually counteracting the energy of pump light in the principle of BOTDA based on electro-optic frequency shift. The hardware and software of signal detection, processing and control circuit based on industrial control computer are designed. The circuit design includes adjustable narrow pulse circuit and photoelectric detection circuit composed of FPGA and high speed amplifier. The adjustable narrow pulse circuit can be controlled by computer to output narrow pulse with arbitrary pulse width, and the minimum pulse width can reach 5 ns. The photoelectric detection circuit is composed of I / V conversion circuit, signal amplifying filter circuit and voltage conversion circuit. It can detect the optical pulse signal whose pulse width is 10 ns and the intensity is less than-50dBm. In signal processing, the signal-to-noise ratio (SNR) of the measured data is improved by pretreatment of sampled data, BOCAX integral, wavelet transform and so on. The nonlinear least square method is used to fit the measured data in Lorentz. Finally, the distribution temperature data are calculated by Brillouin spectrum. The experimental equipment of distributed optical fiber Brillouin temperature measurement system is built. The experimental temperature resolution reaches 10C and the spatial resolution reaches 1m.
【學位授予單位】：北京化工大學
【學位級別】：碩士
【學位授予年份】：2016
【分類號】：TH811
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